Facile synthesis of nanocomposite materials by intercalating an optically active poly(amide-imide) enclosing (l)-isoleucine moieties and azobenzene side groups into a chiral layered double hydroxide

The use of layered inorganic solids as host materials for the creation of inorganic-organic host-guest supramolecular structures is of increasing interest. In the present investigation, the nanocomposites of chiral poly(amide-imide) (PAI) and different amount of modified layered double hydroxide (LDH) were prepared via solution intercalation method for the first time. Chiral organically-modified chiral LDH was prepared via ion exchange reaction of LDH in a solution of N,N′-(pyromellitoyl)-bis-l-isoleucine diacid in distilled water. Novel diamine with azo side group was synthesized from the reaction of 4-aminoazobenzene and 3,5-dinitrobenzoyl chloride followed by reduction of dinitro with iron oxide hydroxide catalyst and hydrazine monohydrate. An optically active PAI was prepared by direct polyamidation of the chiral diacid with azo diamine under green condition using molten tetra-n-butylammonium bromide with good yield and moderate inherent viscosity. The obtained polymer and organically-modified chiral LDH were used to prepare chiral and high performance hybrid materials. The effect of LDH contents on thermal, physicomechanical, and morphological properties of PAI was investigated by Fourier transform infrared spectroscopy, X-ray diffraction, field emission scanning electron microscopy, and transmission electron microscopy techniques. Thermogravimetric analysis results confirmed that the heat stability of the prepared nanoparticle-reinforced composites was improved.